You didn't say why you wanted to remove your data from the cloud (leaving Google is a very good reason though) but I wanted to offer another perspective. I don't like opening up my homefirewall for anything so I have a VPS to host my data in the cloud. It gives me control while still allowing access to my data from anywhere. Kind of a halfway point between self hosting and using public cloud services.
Yes. Run NextCloud on a cheap VPS. File access, online office suite, address book, calendar and a plethora of other applications, and no need to manage hardware or networking.
This. Can be stressfull as wireguard clients update the dns of the endpoint only when the tunnel is restarted. I use a vps inbetween my reverse proxy hat home (internet - vps wg - local wg vm - local reverse proxy)
The NAS can do almost everything you need except offsite C2.
For example Synology ((so far I only had these)) has a built-in DynDNS service that gives you a subdomain you can access the NAS through without extra steps. I bet all the other NAS brands have this built-in as well. Whichever you pick, definitely have 2FA enabled. Also if you can setup your storage pool as btrfs that's great too.
As others pointed out, you need an offsite copy on some C2 provider or a friend's NAS or whatever. (if you've really no budget, you could get a bunch on free subscriptions (dropbox etc.) and split up the backups between them).
The NAS will have an app that already supports a whole lot of providers + things like external USB drive and you can setup automatic backup there.
Depending how important your data is, you may want to consider still backing some of it up to the cloud. You're not going to get the same level of protection with a NAS that you will on the cloud.
I have a decently sized NAS which stores my Plex media and Nextcloud data and will backup Nextcloud daily to Backblaze B2. This way if anything happens to my NAS, I still have my irreplaceable data protected.